Sequential operating system



July 21, W70 w. E. DAVIS ET AL SEQUENTIAL OPERATING SYSTEM 3Sheets-Sheet l Filed March 13, 1968 CONTROLLER FIG...1

I NVENTOR5 JAMES R. ANDERSON BY WAYNE E. DAVIS W,

ATTORNEYS Jply 21, 19 70" gl pgv s IETAL 3,521,130

SEQUENTIAL OPERATING SYSTEM Filed March 13,1968 3 Sheets-Sheet 2 1CONTROLLER SECTOR sec'ron GENERATOR "GATE GATE INVENTORS JAMES R..ANDERSON ATTORNEYS July 21, 1970 w. E. DAVIS ET AL SEQUENTIAL OPERATINGSYSTEM 3 Sheets-Sheet 5 Filed March 13, 1968 J m m S NEV Y E A v D WA. mR 9 M Y B Y United States Patent 3,521,130 SEQUENTIAL OPERATING SYSTEMWayne E. Davis, Pompano Beach, Fla., and James R.

Anderson, Sunnyvale, Calif., assignors to Robert Trent Jones, Inc.,Montclair, N.J., a corporation of New Jersey Continuation-impart ofapplication Ser. No. 645,222,

June 12, 1967. This application Mar. 13, 1968, Ser.

Int. Cl. H01h 47/14; A01g 27/00 US. Cl. 317-139 13 Claims ABSTRACT OFTHE DISCLOSURE A system for operating a plurality of devices in sequenceusing a single pair of conductors. A series of fast chargeslow dischargeresistance-capacitive control circuits sequentially energize portions ofan essentially two-wire power circuit extending from a power sourcefirst to one device and then to other devices in the order of intendedoperation. Initial charging of one control circuit energizes acorresponding one of the devices to be operated and simultaneouslyprevents current fiow to devices at a greater line distance from thepower source. Interruptions of current from the power source forintervals less than the time required for discharge of eachresistance-capacitive control circuit sequentially advance the flow ofpower from one device to the next device in the order.

This is a continuation-impart of application Ser. No. 645,222, nowabandoned, filed June 12, 1967 by Wayne E. Davis and James R. Andersonwhich is entitled Sequential Operating System.

This invention relates to a system for sequentially operating aplurality of devices in fixed or selective sequence using a single pairof conductors extending from a power source to each of the devices inthe order of intended operation. The system, and variations of it, areof substantial economic advantage, particularly where there are a numberof devices to be operated which are spaced apart at great distances. Asan example, the system is useful for operating sprinkler valves to waterthe fairways and greens of a golf course.

This invention contemplates a circuit having a plurality of fastcharge-slow discharge resistance-capacitive circuits, each arranged in abasic control unit for operating a corresponding device or group ofdevices. Each control unit may be produced as a unitary assembly thatcan be manu factured as an electro-mechanical unit or as a solid statetransistorized circuit. In addition, hybrid systems incorporating anumber of each type of control unit are also feasible. The choice ofconstruction depends upon the particular application in which it isused.

One object of the invention is to provide a system for remotelyoperating a plurality of sprinkler valves in sequence for either thesame or varying periods of time.

Another object is to provide a system for operating a plurality ofdevices in sequence using an essentially twowire power circuit.

A still further object of the invention is to provide a system forremote operation of a plurality of devices either in fixed sequence orin a manner which allows selective operation of several devices or aparticular device.

A still further object of the invention is to provide control units forenergizing in sequence groups of devices which may be connected into anessentially two-wire circuit extending from a power supply to first oneand then sequentially to each of the other groups of devices.

"ice

Various other objects of this invention will become apparent from aconsideration of the following detailed description and the accompanyingdrawings, like parts being identified by like reference numbers andletters throughout.

FIG. 1 is a schematic diagram of the system for operating a plurality ofsprinkler valves;

FIG. 2 is a schematic circuit of an electro-mechanical control unit forpracticing the invention;

FIG. 3 is a schematic drawing illustrating a solid state control unitfor practicing the invention;

FIG. 4 is a graphic illustration of the sequential operation of thesystem of FIG. 1 by reference to line voltage versus time;

FIG. 5 is a schematic circuit diagram of one form of power source usefulfor practicing the invention;

'FIG. 6 is a block diagram of a centralized system which employs theinvention; and

FIG. 7 graphically illustrates the time relationship of control pulsesfor the system of FIG. 6.

FIG. 1, of the drawings shows a plurality of sprinkler valves V, each ofwhich is opened by energizing a corresponding one of solenoids S. Anoperating circuit for energizing the solenoids comprises a pair of wiresor other conducting means 10 and 11 supplied with low voltage directcurrent from power source 12. The power is applied to a plurality ofcontrol units 13 and to valve solenoids S by means of an essentiallytwo-wire circuit which extends from the power supply, first to onecontrol unit and corresponding valve solenoid, and then sequentially toother control units and their corresponding valve solenoids in the orderof intended operation. The number of control units provided and requiredfor the circuit shown in one less than the number of valves operated, or11-1.

A controller 14 is employed to periodically interrupt the power supplyor line voltage as applied across conducting means 10 and 11 and,thereby, to step the system. The controller may be a simple manuallyoperated switch but a preferred form of controller permits automaticinterruption of the line current for predetermined times and atpredetermined intervals. For example, a clock-operated stepping switchsuch as a Buckner Model 611E irrigation controller may be used. Itspurpose and function, to interrupt the line current, is hereinafterexplained in detail in connection with operation of the system shown inFIG. 1.

FIG. 2 illustrates a preferred form of electro-rnechanical control unithaving essentially four terminal connections. An input terminal 20connects the positive side of the D-C power source 12 through a normallyclosed relay to an output terminal 21. Input terminal 20 of the firstcontrol unit of the series connects directly to the power source 12through conductor 10 whereas the input terminal 20 of subsequent controlunits in the series connects the positive side of the power sourcethrough the output terminal 21 of the preceding control unit in thesequence. A third or common terminal 22 of each control unit isconnected to the negative conductor 11, or ground; and control terminal23 connects with the device to be operated. In the embodiment shown,terminals 23 connect with one side of solenoid coils 24, respectively,each coil having its other side connected to negative conductor 11 orground.

The circuit of each control unit more particularly comprises a capacitor25 connected in series with a unidirectional current passing means, suchas a diode 26, and a resistor 27, between terminals 20 and 22. A secondre sistor 28 (having a relatively higher resistance than 27) is inparallel with diode 26 and resistor 27, connecting the juncture betweencapacitor 25 and diode 26 to ter- 3 minal 22. A relay coil 29 alsoconnects that juncture through diode 30. The values of resistors 27, 28and diode 26 are selected to develop in capacitor 25 a fast chargingrate and a rleatively slower discharge rate.

Application of line voltage to the control unit rapidly chargescapacitor 25 through diode 26 and resistor 27. Part of the chargingcurrent also flows through diode 30 to energize relay coil 29. Theenergized relay coil 29 opens the normally closed contactor 31 of asingle-pole, double throw relay. The contactor 31 simultaneously closesnormally open relay contact 32 and establishes both a holding currentthrough diode 33 and relay coil 29 to terminal 22 and an operatingcurrent to terminal 23, thereby energizing solenoid coil 24. Terminal 23and normally open relay contact 32 connect with negative terminal 22through diode 34 to protect contacts 31, 32 upon their opening.

Thus, the initial charging of capacitor 25 immediately energizes relaycoil 29 to open the normally closed electrical connection between inputand output terminals 20, 21 of the control unit. This simultaneouslydisables subsequent control units, connects full line voltage across thecorresponding solenoid coil 24 and directs a holding current through therelay coil to maintain this solenoid in operating condition.

An interruption of the line current, for a time interval insufficient todischarge capacitor 25 completely, breaks the holding circuit throughthe now closed but normally open contact 32. This interrupts the flow ofcurrent through relay coil 29 and solenoid coil 24, contactor 31returning to its normally closed position shown in FIG. 2. But theslowly decaying capacitor discharge current prevents the relay fromreopening upon reapplication of full line voltage during that intervaland, thus, full line voltage passes through the closed relay to thesucceeding control unit. On the other hand, an interruption of the linecurrent for an interval of time sufiicient to permit complete dischargeof capacitor 25 will, in effect, reset the control unit, and thereapplication of full line voltage will then cause the circuit to againfunction as previously described.

In the complete system of FIG. 1, therefore, a brief interruption ofpower (of duration less than the time for complete discharge of acontrol unit capacitor 25) advances the operating sequence by onecontrol unit, the reapplication of power operating the next controlleddevice in the sequence and disabling those subsequent to it. But alonger interruption, one which is long enough for all charged capacitors25 to fully discharge, resets the system. Reapplication of power thenoperates the first control unit in the series.

The following component values for the control unit of FIG. 2 aresuitable for operating conventional Skinner irrigation valve coils on a24-volt system:

Capacitor 25-100 mf.

Diode 26-1N34A Resistor 276.8K

Resistor 28-47K Relay (29, 31, 32)MR 201 Gordos Reed Diode 30, 33,34-1N457A FIG. 3 illustrates a control unit made up with solid statecomponents for operating the system in essentially the same manner asthe control unit of FIG. 2. Here again, input terminal 40 connectseither to positive conductor or to the output terminal of a precedingcontrol unit, and output terminal 41 is connected with either the inputof the next control unit or the operated device of the last device inthe sequence. The negative or ground terminal of the control unit is 42and the control terminal is 43.

This control unit comprises capacitor 45 connected in series withresistor 46 and a unidirectional current passing means, such as diode47, between terminals 40 and 42. Initial charging of capacitor 45through resistor 46 and diode 47 places a positive bias on the base of atransistor 48 through base resistor 49. The collector of transistor 48is connected to conductor 10, and its emitter connects to ground throughresistor 50. The positive bias permits a pulse of current to flowthrough transistor 48. Simultaneously, current flows through resistor 51connected between the emitter of transistor 48 and the base of siliconcontrolled rectifier 52. The bias applied to the base initiates a flowof current from terminal 40 through SCR 52 to control terminal 43,energizing solenoid coil 53. The flow of current through the SCR alsoplaces a positive bias on the base of switching transistor 54 throughbase resistor 55. This permits a flow of current through transistor 54from terminal 40 to terminal 42, connected to its collector throughresistor 56. The collector of transistor 54 also directly connects tothe base of switching transistor 57, having its collector and emitterrespectively connected to terminals 40 and 41. A current flow throughtransistor 54 to ground places a positive bias on the base of transistor57, prohibiting current flow through the latter.

The silicon controlled rectifier 52 and transistors 54 and 57 functionessentially the same as the electro-rnechanical relay in the controlunit shown in FIG. 2. Placing an initial charge on capacitor 45 starts aflow of current through the SCR that energizes the solenoid coil 53 andinterrupts the power to those control units and devices at a greaterline distance from the power source. Although the flow of currentthrough transistor 48 ceases after capacitor 45 is fully charged, theSCR continues to pass current to coil 53 and to place a positive bias ontransistor 55 until the line current across conductors 10 and 11 isinterrupted.

A solid state control unit for operating a plurality of conventionalSkinner irrigation valve coils on a 24-volt system may be made up withthe following component values:

Transistors 48, 572N3567 Transistor 54-2N3538 SCR 52MCR2304-1 Diode471N34A Capacitor 4510 Inf. Resistors 46, 561K Resistor 49-18K Resistor501.5K

Resistor 51-10 ohms Resistor 554.7K

The control unit and system in which it is used also allows selectiveoperation of a particular controlled device. This is done simply bymaking a series of short interruptions in the power to conductors 10 and11 to step the system until the desired control unit capacitor ischarged and its controlled device operated. The interruptions may bedone manually. But, as previously indicated, controller 14 may also beprogrammed to briefly interrupt the line current for the number of timesnecessary to select out a particular valve. In either case, briefinterruptions of power advance the sequence of valve operation, whileinterruptions of power for intervals which allows the capacitors todischarge, reset the entire system. The particular duration of powerinterruption required to step or to reset the system is, of course,determined by the size of capacitors and resistors which make up thetime delay circuit in the control units.

In those applications of the invention where it is desirable to stepthrough the sequential system and oper ate a particular device withoutactuating preceding devices, it is often better to advance throughcontrol units, as described above, at a voltage lower than the thresholdoperating voltage of the valve solenoids S, for example. Upon reachingthe particular device to be operated, the applied line voltage is thenincreased to the normal operating voltage required. In order not toupset or reset the charged capacitors, the voltage should be increasedslow- 1y, allowing all preceding control unit capacitors on the line totake up their full charge. For the Skinner valves and control unitsdescribed in connection with FIGS. 1 and 2, the sequence is preferablystepped at a 12 volt level, and the voltage is then increased to 24volts to operate a particular valve.

FIG. 4 illustrates a representative time cycle for operating the systemof FIG. 1 with either the control units of FIG. 2 or 3 and using apreferred form of power supply having a maximum voltage of 24 volts. Thepower supply in this instance is one that will cut back to half voltagefor a brief period after each interruption and which then slowlyincreases until full voltage is attained. The curve of FIG. 4 is a plotof line voltage (as applied across conductors 10 and 11) versus time,and it particularly depicts the line current for operating the first andfourth control units only.

In the exemplary cycle of operation represented by the curve of FIG. 4,the line current is initially set to off or interrupted by controller 14for a period of time T, sufiicient to discharge all control unitcapacitors. Controller 14 is then operated, as for example by closingcontacts in power source 12, to apply an instantaneous 12 volt linecurrent across conductors 10 and 11. The line current rises slowly aftera brief delay T and increases until it attains a maximum operatingvoltage of 24 volts, the voltage desired for operating solenoids S ofthe sprinkler valve described. Although the capacitor of the firstcontrol unit 1 is immediately charged during the period T the associatedsolenoid and sprinkler valve will not be actuated until the thresholdoperating voltage is reached. (The threshold voltage for Skinner valvesdescribed above is about 16-20 volts.) Following the brief delay time,and after the threshold voltage is attained, the valve associated withcontrol unit 1 is opened and remains open until the current isinterrupted.

At the end of the period T the line current is interrupted by a seriesof three pulses, each interruption being for a period of time T a periodsufficient for deactivat ing the solenoids but insuflicient to permitfull discharge of the control unit capacitors. The brief period of timeT (during which the current is reapplied) follows each interruptionperiod T The time period T is preferably less than the period requiredfor building up the line current to maximum operating voltage.Accordingly, neither of the solenoid valves controlled by units 2 or 3are actuated. The reapplication of line current after the third pulseinterruption, however, increases in a manner previously described withrespect to control unit 1 until the solenoid and sprinkler valveassociated with control unit 4 are operated, and that valve remains openuntil the end of period T.;,. The gradual rise in the line voltage, from12 to 24 volts, allows the control capacitor of control units 1 through4, which have been previously charged and partially discharged, to pickup the full charge at the 24 volt level without upsetting the system.

In some applications, of course, the controlled devices may be operatedmomentarily without objection. In such instances, the stepping operationmay be carried out at full line voltage. However, to avoid difficultieswith the seating of sprinkler valves, it is desirable that the steppingfunction proceed at a value less than that which will operate thesprinkler solenoids.

FIG. 5 illustrates a power source which provides the desired voltagechanging function described above. It includes a supply 60 of 24 voltD-C power; a low voltage circuit means 61 which supplies power at the 12volt level across conductors 10, 11; high voltage circuit means 62 forproviding a slowly rising voltagewaveform from 12 volts to a 24 voltlevel; and relay means actuated by controller 14 to provide a resetinterruption of long duration, stepping interruptions of shorterduration and the shaped change from the 12 to 24 volt operating level.

The power supply 60 comprises a step-down transformer 63 which reducesA-C line voltage to 24 volts; a

6 diode bridge including diodes 65a, 65b, 65c and 65d which rectifiesthe transformer output to D-C; and filter condenser 66. One side of thesupply is grounded.

Transistor 67 having its collector connected to the positive 24 voltsupply through resistor 68 normally supplies 12 volt D-C power acrossconductor 10 and D-C grounded conductor 11. The base is biased by directconnection to the emitter of transistor 69 which has its collectordirectly connected to the collector of transistor 67. A 12 volt Zenerdiode 70 in series with resistor 71 between ground and the base oftransistor 69 regulates the bias on transistor 69 at 12 volts. Thus,when conducting, the emitter of transistor 67 delivers power at 12 voltsto conductor 10 through normally closed relays 72, 73, which ashereinafter described, provide reset and stepping interruptions in thepower supplied. Resistor 74 and condenser 75 bypass the emitter outputto ground. Capacitor 77 connects the emitter and capacitor 78 connectsthe collector of transistor 69 to ground. Resistor 79 connects itscollector to the juncture between base resistor 71 and Zener diode 70and capacitor 76 connects that juncture to ground.

Both of relays 72 and 73 are normally closed and connect power toconductor 10 as shown in FIG. 5. The coil of relay 72 receives periodicreset pulses from controller 14 through terminal 80. The control pulsesopen relay 72 to D-C ground and, thus, provide an interruption in thepower supplied to conductors 10 and 11 of a duration sufficient to resetthe system as hereinabove described. The coil of relay 73, on the otherhand, receives control pulses of shorter duration from controller 14 atterminal 81 which open relay 73 to ground and interrupt the power forperiods of short duration for stepping the sequence of the controlunits.

The high voltage circuit means 62 on command of a control pulse throughterminal 82 from controller 14 supplies 24 volt power across conductors10 and 11 with a waveform which has a slowly rising leading edge fromthe 12 volts supplied by circuit means 61, as shown in FIG. 4.Transistor 83 having its collector and emitter connected in common withthose same elements of transistor 67 supplies the rising voltage oncommand through relays 72, 73. The base of transistor 83 connects groundthrough resistor 84 and is biased by direct connection to the collectorof amplifier transistor 85, the emitter of which connects directly tothe 24 volt D-C supply. The collector of a second amplifier transistor86 biases the base of transistor through resistor 87. Resistor 88 andcapacitor 89 also connect the base of transistor 85 to the 24 voltsupply. The emitter of transistor 86 connects ground.

Transistor 90 having its collector directly connected to the 24 voltsupply biases the base of amplifier transistor 86 through its emitterresistor 91. Zener diode 92 connected from ground through resistor 93 tothe 24 volt supply provides a 3.6 volt bias on the base of transistor 90through series resistors 94 and 95. Capacitor 96 connects the junctureof these two resistors to ground and is parallel with Zener diode 92.Capacitor 96 is normally charged but can be shorted and discharged toground by the closing of normally open relay 97 in parallel with it.

The power source of FIG. 5 normally provides a 12 volt output throughtransistor 67 which may be inter rupted to provide the stepping functionby control pulses supplied to relay 73 or the reset function by a longercontrol pulse supplied to relay 72. Then, when the sequence has beenstepped to a particular valve which must be operated, controller 14supplies a control pulse to terminal 82 which closes relay 97. It shortsout capacitor 96 to ground and the capacitor discharge varies theresulting bias on the base of transistor 90 and through it on transistor86. Transistors 86 and 85 amplify and apply the discharge wave form toreduce the base bias of transistor 83. Transistor 83 then conducts andsupplies 24 volts to conductor 10. Transistor 67 turns off. But theamplified wave shape of the discharging capacitor 96 retards the rise inthe output voltage of transistor 83 so that capacitors in each precedingcontrol unit can slowly pick up their charge to the full 24 volt levelwithout upsetting the system.

Appropriate values for the circuit which is shown in FIG. are asfollows:

Diode bridge 65a65d-Motorola MDA 9522 Transistors 67, 83-RCA 40316'Resistor 68-2 ohms Transistors 69, 86, 902N35 67 Zener diode 70-1N4744Resistor 71, 87, 931K Resistor 74, 956.8K

Capacitor 66, 75, 76, 78, 96500 mf. Capacitor 77-l0 mf.

Resistor 79'680 ohms Resistor 8447K Transistor 85--2N1183 Resistor'8833ohms Capacitor 89l00 mf.

Resistor 91-15K Zener diode 92-1N4729, 3.6 volts Resistor 944.7K

There are many ways in which more complex systems may be used tocomplement the basic control units and system described above. Forexample, the controlled devices may be grouped into gated sectors, eachof which employs the sequential circuitry described. The gated sectorsmay be selectively opened, for example by a variety of command signalssuch as tones, varying pulse width, plus frequency, etc.

FIGS. 6 and 7 illustrate the invention employed in a centralized systemwherein the controller 14 and pulse generating means, such as pulsegenerator 100, are housed in a central control station. At the commandof controller 14' the pulse generator emits programmed pulse trainswhich conductors 101 and 102 transmit to a series of remote sector gates103 each of which sequentially or selectively operates one or morecontrolled devices grouped in the sector through a series (1, 2, etc. or11, 12, etc. or 51, 52, etc.) of control units 13. The system employestwo control conductors 101, 102 and a common ground 104. Conductor 101supplies sector gate stepping and reset signals to the series of sectorgates 103. Conductor 102 supplies control unit stepping and resetsignals for actuating the control units 13 in the several sectors. Eachsector gate comprises essentially a control unit circuit similar to thatin FIG. 2 or 3 in combination with a power source circuit similar tothat of FIG. 5.

The controlled pulse generator 100 supplies to conductor 101 a series oflong pulses 105 separated by short interruptions 106, as shown in FIG.7, which step the sector gates 103 in the manner heretofore describedfor the control units of the system in FIG. 1. For this purpose eachsector gate includes, for example, a control unit circuit 13 as shown inFIG. 2 with the circuit values modified to accommodate a steppinginterruption of different (longer) duration than the steppinginterruptions for the control units in the sectors. Thus, the pulse 105charges a condenser comparable to 25 in the first sector gate 103; opensa normally closed contactor 31 to disconnect conductor 101 from sectorgates subsequent to it in the series; and closes a normally opencontactor 32 to conduct the pulse in conductor 101 as a holding currentthrough a relay coil 29.

The relay coil in the control unit circuit of the first sector gate atthe same time closes another normally open contactor that connectsconductor 102 to the power source circuit in the sector gate which issimilar to that shown in FIG. 5. The arrival of pulse 107 in conductor102 opens a normally closed relay, such as 72 of FIG.

5, and interrupts power supplied by the first sector gate 103 toconductor 10 for a duration sufficient to reset all control units 13grouped in the first sector (1, 2, etc.). The pulse in 102 also opensswitching means, such as relay 97 of FIG. 5, to charge a capacitor 96 sothat the sector gate power circuit will supply only 12 volts acrossconductors 10 and 11 to the first sector control units.

If the controller program calls for operation of the first and fourthsprinklers in the first sector, for example, an operating interruption108 in conductor 102 then enables relay 72 to close and connect 12 voltpower of the sector gate power circuit to conductor 10 of the firstsector. This actuates the first control unit of the first sector as isshown in FIG. 7 at 109. The same interruption enables relay 97 to closeand switch capacitor 96 to ground. The power supplied then rises from 12to 24 volts and operates the solenoid of the first sprinkler of thefirst sector. This sprinkler operates until stepping pulse 110 appearsin conductor 102 to produce a corresponding stepping interruption 111 inconductor 10' which is of ditferent (shorter) duration than that of thegate stepping interruptions 106.

As is described in connection with FIG. 4, this first steppinginterruption 110, 111, is sufficient to deactivate the solenoid of thefirst sprinkler valve but is insufficient to permit full discharge ofthe capacitor 25 in the first control unit of that sector. The briefinterruption 112 in conductor 102 and the corresponding reapplication ofpower in conductor 10 of the first sector at 12 volts, as at 113, isless than the period required for complete discharge of capacitor 96.Accordingly, the power supplied does not rise beyond 12 volts and thesolenoid valve of control unit 2 in the first sector is not actuated.The subsequent pulse 114 in conductor 102 and the correspondinginterruption 115 in conductor 10' of the first sector steps the sequenceto the third control unit. The following interruption 116 in conductor102 and corresponding 12 volt pulse 117 in conductor 10 charges thecapacitor of the third control unit but is not sufficient to actuate thesolenoid.

Finally pulse 118 in conductor 102 and the corresponding interruption119 in conductor 10' steps the sequence to the fourth control unit inthe first sector. Interruption 120 in conductor 102 as in the case ofinterruption 108 is of sufficient duration to permit sector gate powersupply to rise in voltage from the 12 volt to the 24 volt level as at121 and operate the fourth solenoid valve in the first sector. Itcontinues in operation in the example of FIG. 7 until the next sectorgate stepping interruption 106 appears in conductor 101. This, ofcourse, opens a contactor 32 in the control unit circuit of the sectorgate and the other normally open contactor associated with it thatheretofore had connected conductor 102 to the power source circuit ofthe first sector gate. This interruption 106 steps the gating sequenceto the second sect-or gate. There is no further operation of controlunits or solenoid valves in the first sector. The general sequence asherein described for the first sector is repeated for the second sector,etc. depending on the program of controller 14.

After all programmed sprinklers in all sectors are operated, a resetinterruption 122 in conductor 101 of longer duration than interruption106 resets the sector gate control unit circuits as previously describedin connection with FIGS. 1 and .2.

The pulse generator 100 in the embodiment of FIG. 6 provides twoseparate series of square wave pulses, one which forms the steppinginterruptions 106 in conductor 101 for the sector gates and the otherwhich supplies the shorter stepping pulses in conductor 102 andcorresponding stepping interruptions for control units in the varioussectors. The controller v14 superimposes on these continuous pulsesinterruptions or pulses of longer duration such as 107, 108, 120 and 121to provide the valve 9 operating and stepping functions which weredescribed in the example of FIG. 7.

Although one particular system and several embodiments of the inventionhave been illustrated and described, it is to be understood that variousmodifications and changes may be made without departing from the spiritof the invention or the scope of the attached claims, and each of suchmodifications and changes is contemplated.

We claim:

1. A sprinkler system having a plurality of normally closed sprinklervalves; a plurality of solenoids each for operating a corresponding oneof said valves; a power source to energize said solenoids; a circuit foroperating said solenoids to open said valves in predetermined sequencecomprising an essentially two-wire conducting means for carrying currentfrom said power source to first one and then to each of the other ofsaid solenoids, a plurality of control units for selectivelyinterrupting the flow of current through said conducting means be tweensaid solenoids, each of said control units having interrupting means forinterrupting the flow of current through said conducting means to thesolenoids of valves subsequent to it in said sequence, operating meansresponsive to the normal line current of said power source for operatingsimultaneously said interrupting means and the solenoid preceding saidinterrupting means, and a fast charge-slow discharge capacitive circuitthat disables said operating means upon application of normal linecurrent following a stepping interruption of short duration and enablesit upon application of normal line current following a resetinterruption of longer duration; and control means interrupting powerfrom said power source with stepping and reset interruptions in accordwith said predetermined sequence.

2. A sprinkler system according to claim 1 wherein said power sourcedelivers normal line current at a low stepping voltage level followinginterruption by said control means for a time period at leastcommensurate with said stepping interruption and, subsequent to saidtime period, delivers power which slowly rises in voltage to a higheroperating level.

3. A circuit for operating in predetermined sequence a plurality ofelectrically operable devices from a power source comprising anessentially two-wire conducting means for carrying current from saidpower source to first one and then to each of the other of said devices;a plurality of control units for selectively interrupting the flow ofcurrent through said conducting means between devices, each control unithaving an interrupting means to disconnect said conducting means fromthose control units and devices subsequent to it in said sequence,operating means responsive to the normal line current of said powersource for operating simultaneously said interrupting means and thedevice preceding said interrupting means, and a fast charge-slowdischarge capacitive circuit that disables said operating means uponapplication of normal line current following a stepping interruption ofcurrent from said power source of short duration and enables it uponapplication of normal line current following a reset interruption oflonger duration.

4. The operating current of claim 3 wherein the power source suppliesdirect current and each control unit includes a capacitor; a relayhaving normally closed contacts in series with said conducting means,and a relay coil in series with said capacitor, said capacitor and relaycoil being connected across said conducting means with the chargingcurrent of said capacitor energizing said relay coil; and a holdingcircuit for said relay that is enabled during charging of said capacitorand disabled upon interruptions of power from said power source forstepping intervals insufiicient to fully discharge said capacitor.

5. The operating circuit of claim 4 wherein said relay includes a pairof normally open contacts which close and apply current to one of saiddevices when said relay coil is energized.

6. The operating circuit of claim 4 wherein said capacitive circuitincluding said capacitor delays full discharge of said capacitor for atime period greater than said stepping interruption.

7. The operating circuit of claim 3 wherein said control unit includes anormally conducting transistor having emitter and collector connected inseries with said conducting means, a capacitor, and means activated bythe full charging current of said capacitor for biasing the base of saidtransistor to terminate conduction of said transistor and the flow ofcurrent through said conducting means to those control units and devicessubsequent to it in said sequence.

8. The operating circuit of claim 7 wherein the power source suppliesdirect current and said capacitive circuit including said capacitordelays full discharge of said capacitor for a time period greater thansaid stepping interruption.

9. A control unit for energizing only one of a number of electricallyoperable devices in a sequence relative to other devices of said number,and which may be connected into an essentially two-wire power circuitextending from an interruptable power source to first one and thensequentially to each other device in the order of intended operation,comprising an interrupting means that may be connected in series withone wire of the power circuit, operating means responsive to the normalline current of said power source for operating simultaneously saidinter rupting means and the device preceding said interrupting means,and a fast charge-slow discharge capacitive circuit that disables saidoperating means upon application of normal line current following astepping interruption of current from the power source of short durationand enables it upon application of normal line current following a resetinterruption of longer duration.

10. The control unit of claim 9 wherein said interrupting meanscomprises the normally closed contacts of a relay; said operating meanscomprises the normally open contacts and the coil of said relay and aholding circuit between said normally open contacts and said coil; andsaid fast charge-slow discharge capacitive circuit is con nected to thecoil of said relay.

11. The control unit of claim 9 wherein said interrupting meanscomprises a switching transistor; said operating means includes acontrolled rectifier biasing the base of said transistor; and saidrectifier is connected to said fast charge-slow discharge capacitivecircuit to bias the base of said transistor to interrupt the currentflowing therethrough when current fiows through said rectifier.

12. A power source including means for normally supplying power at a lowstepping voltage level; means which upon command supplies power at ahigher operating voltage level and simultaneously discontinues powersupplied at said stepping voltage level; and voltage inhibiting meansdelaying the rise time of the power output from said low stepping tosaid higher operating voltage level.

13. A sprinkler system having a plurality of solenoidoperatednormally-closed sprinkler valves grouped into at least two sectors;sector gate means for each sector; a first conductive means connectingsaid sector gates in series; each of said sector gate means havinginterrupting means for interrupting the flow of current through saidfirst conductive means to the sector gate means subsequent to it in theseries, operating means for simultaneously supplying power to thesolenoids in its sector and its interrupting means, and a fastcharge-slow discharge capacitive circuit that disables said operatingmeans upon application of normal line current in said first conductivemeans following a stepping interruption of short duration and enablessaid operating means upon application of normal line current in saidfirst conductive means following a reset interruption of longerduration; 21 second conductive means connecting in series the solenoidsof each of said valves in a sector; a plurality of control units forselectively interrupting the flow of current through said secondconducting means between said solenoids, each of said control unitshaving interrupting means for interrupting the fiow of current throughsaid conducting means to the solenoids of valves subsequent to it insaid sector, operating means responsive to normal line current of saidsector gate for operating simultaneously said interrupting means and thesolenoid preceding said interrupting means, and a fast charge-slowdischarge capacitive circuit that disables said operating means uponapplication of normal line current in said second conductive meansfollowing a stepping interruption of short duration and enables it uponapplication of normal line current in said second conductive meansfollowing a reset interruption of longer duration; and control pulsemeans for supplying interruptions of power in said first conductivemeans to step said sector 12. gate means in predetermined sequence andfor supplying through said sector gate means stepping interruptions ofdifferent duration to said second conductive means to step the controlunits of said valves in each of said sectors and to operate thesolenoids of each sector in a predetermined sequence.

References Cited UNITED STATES PATENTS 3,124,722 3/1964 Steiner 317-4393,215,916 11/1965 Hermann 317139 X 3,232,317 2/1966 Fowler 317-141 X LEET, HIX, Primary Examiner US. Cl. X.R. 30741, 154

